Process for the production of an improved simulated casein from proteinaceous mixtures

ABSTRACT

A process is disclosed for producing an improved modified plant protein having thermoplastic and forming properties similar to casein and caseinate salts. The process comprises making an aqueous slurry of a plant protein material and an alkali metal carbonate, adjusting the pH, reacting the carbonate with the protein, admixing the slurry with a peroxide, neutralizing the slurry, removing steam volatile flavor components, drying the neutralized slurry, and then blending the dried modified proteinaceous slurry with an unmodified proteinaceous material. The process produces a product which is improved in odor, taste and color.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for producing an improved modifiedplant protein having thermoplastic and forming properties similar tocasein and caseinate salts. The process involves the reaction of analkali metal carbonate with plant protein to produce a reaction product.Peroxide is then added to the reaction product and the peroxidecontaining reaction product is then neutralized. The reaction product isthen heated under a vacuum.

2. Description of the Prior Art

Casein, a milk protein, and its salts are used extensively in the foodindustry to manufacture fabricated food products. One of the majorreasons for the popularity of casein and caseinate salts in fabricatedfoods is its unique functional properties such as high water solubilityand the thermoplastic behavior of caseinate-water mixtures. Bythermoplastic behavior, in this context, is meant the ability of aprotein dough to flow freely like a liquid upon application of heat anda return to a semi-solid elastic mass upon cooling to ambienttemperatures. Unmodified plant proteins generally lack this property andtherefore cannot be used as a functional replacement of caseinate saltsalthough the cost considerations favor their use. U.S. Pat. Nos.3,917,877, 3,917,878, 3,917,879, and 3,930,058 have described processesused to modify plant proteins to simulate the thermoplastic propertiesof casein or caseinate salts. In all of the processes taught in theabove patents, unmodified plant protein was treated with alkali. Thealkali treatment of plant protein produces a product having a muddygreen color and a strong odor characteristic of hydrogen sulfide. It hasbeen observed that the color, odor and flavor of the alkali treatedplant protein is highly objectionable and undesirable.

We have now developed a process by which the flavor and color ofalkali-modified plant protein can be improved to yield a protein ofhighly desirable creamy white color and bland flavor. According to thedeveloped process, the alkali-modified solution of plant protein or amixture of plant and animal protein is reacted with a peroxide solution,followed by removal of steam volatile flavor components. The latter maybe accomplished by heating the peroxide treated protein solution under avacuum and removing the vapors. The relative amount of peroxide addedand the time and temperature of peroxide treatment determine the extentof improvement in color, odor and flavor.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a process for producing amodified plant protein with improved odor, taste, and color, having thethermoplastic and binding properties of casein and caseinate salts.

The object of this invention is accomplished by a process for producinga modified plant protein having properties similar to casein andcaseinate salts and having improved odor, taste and color, said processcomprising:

a. making an aqueous slurry of a vegetable protein material, said plantprotein material containing at least about 30 percent by weight protein;

b. adjusting the pH of the aqueous slurry to a pH in the range of fromabout 7.0 to about 10.5 by addition thereto of an alkali metalcarbonate;

c. heating the aqueous slurry to react the alkali metal carbonate withthe protein;

d. cooling the slurry to a temperature within the range of from about60° F. to 130° F.

e. adding from about 0.3 percent to about 2.0 percent by weight peroxideto the slurry per pound of protein;

f. mixing the peroxide containing slurry;

g. neutralizing the slurry to a pH of from 6.6 to 7.0 by additionthereto of an edible acid;

h. thereafter, heating the slurry under a vacuum to removesteam-volatile flavor substances;

i. drying the neutralized slurry to remove a substantial portion of thewater therein; and

j. admixing from 1 to 15 parts by weight of the neutralized and modifiedslurry with from 1-30 parts by weight unmodified proteinaceous material.

The object of this invention is also accomplished by a process forproducing a modified plant protein having properties similar to caseinand caseinate salts and having improved odor, taste and color, saidprocess comprising:

a. making an aqueous slurry of a vegetable protein material, said plantprotein material containing at least about 30 percent by weight protein;

b. adjusting the pH of the aqueous slurry to a pH in the range of fromabout 7.0 to about 10.5 by addition thereto of an alkali metalcarbonate;

c. heating the aqueous slurry to react the alkali metal carbonate withthe protein;

d. cooling the slurry to a temperature within the range of from about60° F. to 130° F.

e. adding from about 0.3 percent to about 2.0 percent by weight peroxideto the slurry per pound of protein;

f. mixing the peroxide containing slurry;

g. neutralizing the slurry to a pH of from 6.6 to 7.0 by additionthereto of an edible acid;

h. thereafter, heating the slurry under a vacuum to removesteam-volatile flavor substances; and

i. admixing from 1 to 15 parts by weight of the neutralized and modifiedslurry with from 1-30 parts by weight unmodified proteinaceous material.

Preferably, the process includes a cooling step, say down to a range offrom about 60° F. to 130° F., after the heating-reacting step and priorto the neutralization step.

More preferably the protein material of this invention is a solventextracted oil seed vegetable protein.

It is also preferable that the aqueous slurry of this invention has asolids contents of about 3 percent to about 18 percent by weight, and aprotein content up to about 12 percent by weight.

The preferred alkali metal carbonate of this invention is a memberselected from the group comprising sodium carbonate, sodium bicarbonate,potassium carbonate, and potassium bicarbonate.

The preferred peroxide of this invention is a member selected from thegroup consisting of hydrogen peroxide, sodium peroxide, potassiumperoxide, calcium peroxide and magnesium peroxide.

The preferred reaction temperature of this invention is a temperature offrom 280° F. to 370° F. in a closed vessel for 21/2 to 5 minutes.

DETAILED DESCRIPTION OF THE INVENTION

The first step in this invention requires making an aqueous slurry of aplant protein material. Preferably, the protein material is an oil seed,solvent extracted, plant protein such as soy protein isolate or soyprotein concentrate. Other proteins, however, such as oat protein, havebeen found to be highly acceptable for use in this invention. Other oilseed vegetable proteins, solvent extracted to concentrate the proteintherein are also acceptable, such as peanut and sesame protein and theother oil seed vegetable proteins. It is preferred that the proteinmaterial contain at least about 30 percent by weight protein.

The aqueous slurry is prepared simply by adding the proteinaceousmaterial to water and mixing until a slurry is provided. Preferably theslurry is prepared by mixing from 3 to 18 percent by weight of theproteinaceous material in water and mixing until a slurry is formed.This preferably gives an overall protein content in the slurry of up toabout 12 percent by weight.

The next step in the invention requires adjusting the pH of the aqueousslurry to a pH in the range of from about 7.0 to about 10.5 by additionthereto of an alkali metal carbonate. It is important and critical tothe invention that the aqueous slurry have a pH above 7.0 in order tocarry out the complete process of this invention. This can generally beaccomplished by adding from about 0.5 to 4.0 percent by weight of thealkali metal carbonate. By use herein of the term "alkali metalcarbonate" it is intended to mean the term with its well known useconsisting of the carbonates of the alkali metals as well as thebicarbonates or acid carbonates thereof. For instance, sodium carbonateand potassium carbonate are highly acceptable in this invention as wellas sodium bicarbonate and potassium bicarbonate. It is within thepurview of one skilled in the art that he might achieve the desired pHrange by addition of the carbonate. It is preferable that the pH beadjusted between 7.2 and 10.5. A pH of about 8 is highly preferable.

After the pH has been adjusted by addition of an alkali metal carbonatethe aqueous slurry is heated to react the alkali metal carbonate withthe protein. The heating must be sufficient to provide a reactionbetween the carbonate and the protein but must be below thedecomposition temperature of the protein. We have found, for instance,that the 330° F. reaction temperature in an enclosed vessel for a timeperiod of from 160-200 seconds produces an acceptable product. We havealso found that a temperature from 295° F. to 310° F. for from 3.5 to 5minutes produces a good product. Other times and temperatures may alsobe utilized, providing the reaction product when neutralized has thesame properties as herein attributed to the above-described reaction. Itis well within the skill of one knowledgeable in the art to preparethese different products with different reactions in order to arrive atan end product. However, the optimum conditions are as stated above. Inany condition, the temperature should be at least above the boilingpoint of water up to a point at which degradation of the proteinmaterial or reaction product occurs. It is preferable that the reactionbe conducted in a closed vessel since this enables heating of theaqueous slurry above the boiling point of water. Generally this willraise the pressure of the reaction to something around 90 pounds persquare inch but this is acceptable in producing a desirable product.

At this point in the process, it is preferable to cool the reacted mass.This can be accomplished by conventional means to arrive at atemperature of from about 60° F. to 130° F.

The next step in this invention requires the addition of a peroxide tothe slurry. The peroxide containing slurry is then thoroughly mixed. Theperoxide can be a member selected from the group consisting of hydrogenperoxide, sodium peroxide, potassium peroxide, calcium peroxide andmagnesium peroxide. The relative amount of the peroxide added and thetime and temperature of peroxide treatment will determine the extent ofimprovement in color, odor and flavor. It is preferable that from about0.3 percent to about 2.0 percent by weight peroxide is added per poundof protein. It is also preferable to add the peroxide to the slurry whenthe slurry is at room temperature.

The next step in this invention requires the neutralizing of the slurryto a pH of from 6.6 to 7.0 by addition thereto of an edible acid. It iscritical that the neutralization produce a pH within the stated range. Amuch lower pH will cause precipitation of the protein. Theneutralization can occur by use of any of the known edible acids whichare normally used as food additives. For instance, hydrochloric acid,citric acid, formic acid and acetic acid, are all members of the groupof edible food grade acids acceptable for use in this invention.

After the slurry has been neutralized and the peroxide has been added,the slurry is heated to remove the steam volatile flavor components. Theremoval of the steam volatile flavor components can be accomplished muchfaster if the slurry is heated under a vacuum, in the range of fromabout 15 inches to about 30 inches and at a temperature sufficient toaccomplish boiling. Preferably, the steam volatile flavor components areremoved from the slurry by heating the slurry to a temperature of 150°F. under a vacuum of 22 inches. By use herein of the term "steamvolatile flavor components" it is intended to mean those substances thathave a boiling point lower than that of water and which impartobjectionable flavors and odors to the alkali modified protein.

After neutralization of the slurry and the removal of the steam volatileflavor substances, the slurry is then dried to remove a substantialportion of the water. The moisture content of the final product shouldbe about 15 percent by weight moisture or lower. Drying can occur in anyof the common commercial processes such as drum drying, spray drying, orfreeze drying, and either process is acceptable for use in thisinvention.

The final step in this process requires admixing from 1 to 15 parts byweight of the neutralized slurry with from 1 to 30 parts by weightunmodified proteinaceous material. The unmodified proteinaceous materialrefers to proteinaceous material that is not modified according to theprocess hereinabove described with relation to modification by alkalimetal carbonate treatment. The unmodified proteinaceous material mayrefer to either plant proteins or animal proteins. In other words, theunmodified proteinaceous material can refer to the oil seed vegetableproteins that are solvent extracted such as soy protein concentrate, soyprotein isolate, or it may refer to oat protein, peanut protein, orsesame protein which has been unmodified or it may also refer to meatprotein such as meaty materials, or to fish protein such as fish flouror fish meal. In other words, the normally acceptable usage of the term"proteinaceous material" is acceptable for admixture herewith to producean acceptable product.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention may be more fully described, but is not limited by thefollowing examples.

EXAMPLE 1

An aqueous slurry of approximately 6 percent by weight soy proteinisolate was prepared by mixing about twenty pounds of soy proteinisolate with about 38 gallons of water at ambient temperature. About 315grams of sodium carbonate was slowly added to the slurry to achieve a pHof approximately 8.0. The protein slurry was then heated at 300° F. for4 minutes and cooled to ambient temperature. The resulting proteinsolution had a muddy green color and a strong odor characteristic ofhydrogen sulfide. Two hundred milliliters of 30 percent hydrogenperoxide was added to the material and the contents were mixed for 30minutes. The pH of the protein solution was adjusted to 7.0 with 1 Nhydrochloric acid and the solution was pumped into a single stage vacuumevaporator. The solution was heated at 150° F. under a vacuum of 22inches, and the resulting vapors were removed. The evaporation wascontinued until the volume in the evaporator was reduced toapproximately half the original volume. The concentrated slurry wasyellowish white in color and had a bland flavor and odor. The productwas then dried in a spray drier until the moisture content thereof wasless than 15 percent by weight. The dried slurry resembled a creamywhite powder with bland flavor and odor. The dried slurry was thenadmixed with unmodified soy protein concentrate in an amount of 3 partsby weight soy protein concentrate to 1 part by weight dried slurry andextruded into a fibrous product having properties similar to casein.

EXAMPLE 2

A procedure similar to that in Example 1 was used except that the pH ofthe alkali-modified slurry was adjusted to 7.0 before adding hydrogenperoxide.

EXAMPLE 3

Same as Example 1 except that 100 grams of sodium peroxide was mixedwith the alkali-modified protein in place.

EXAMPLE 4

Same as Example 2 except that 100 grams of sodium peroxide was added inplace of hydrogen peroxide.

EXAMPLE 5

Example 1 is repeated with the exception that the alkali metal carbonateis potassium carbonate. Again, an acceptable product is produced.

EXAMPLE 6

Example 1 is repeated except the modified plant protein material is oatprotein. Again, an acceptable product is produced.

EXAMPLE 7

Example 5 is repeated with the exception that the modified plant proteinmaterial is oat protein. Again, an acceptable product is produced.

EXAMPLE 8

Example 1 is repeated except the modified plant protein material is amixture of one part by weight oat protein and two parts by weight soyprotein concentrate. Again, an acceptable caseinate replacement isproduced.

EXAMPLE 9

Example 1 is repeated except the modified plant protein material is amixture of one part by weight sesame seed protein and three parts byweight soy protein concentrate. Again, an acceptable caseinatereplacement is produced.

EXAMPLE 10

Example 1 is repeated except the modified plant protein material is amixture of one part by weight peanut protein and one part by weight soyprotein concentrate. Again, an acceptable caseinate replacement isproduced.

EXAMPLE 11

Example 5 is repeated except the modified plant protein material is amixture of one part by weight sesame protein and three parts by weightsoy protein concentrate. Again, an acceptable caseinate replacement isproduced.

EXAMPLE 12

Example 5 is repeated except the modified plant protein material is amixture of one part by weight peanut protein and three parts by weightsoy protein concentrate. Again, an acceptable caseinate replacement isproduced.

EXAMPLE 13

Example 1 is repeated with the exception that the unmodified protein isground meat. Again, an acceptable product is produced, in which thebinding characteristics of sodium caseinate are found.

EXAMPLE 14

Example 5 is repeated with the exception that the unmodified protein isground meat. Again, an acceptable product is produced.

EXAMPLE 15

Example 6 is repeated except the unmodified protein is ground meat.Again, an acceptable product is produced.

EXAMPLE 16

Example 7 is repeated with the exception that the unmodified protein isground meat. Again, an acceptable product is produced.

EXAMPLE 17

Example 8 is repeated with the exception that the unmodified protein isground meat. Again, an acceptable product is produced.

EXAMPLE 18

Example 9 is repeated with the exception that the unmodified protein isground meat. Again, an acceptable sodium caseinate replacement isproduced.

EXAMPLE 19

Example 10 is repeated with the exception that the unmodified protein isground meat. Again, an acceptable caseinate replacement is produced.

EXAMPLE 20

Example 11 is repeated with the exception that the unmodified protein isground meat. Again, an acceptable sodium caseinate replacement isproduced.

EXAMPLE 21

Example 12 is repeated with the exception that the unmodified protein isground meat. Again, an acceptable sodium caseinate replacement isproduced.

While it is not desired to be bound by any particular theory coveringthe operation of this invention, nevertheless, the following postulateis offered in relation to the use of the peroxide.

We believe the alkali treatment induces at least two types of reactionsthat contribute towards the objectionable flavor, odor and color of thetreated slurry. It is believed that one of these reactions involves thealkali metal carbonates acting on the sulfur-containing amino acids in aprotein thereby producing a number of low molecular weight sulfurcontaining compounds such as hydrogen sulfide and thiols. Thesecompounds and others produced through secondary reactions are normallyvolatile and impart unacceptable flavor and color to the protein. Wefurther believe that the other reaction occurs in the presence of alkaliand at elevated temperatures. Under these conditions proteins react withcarbohydrates to produce chemical compounds that impart brown color andobjectionable flavor. The compounds produced in both reactions aremostly reducing compounds. Since peroxides are potent oxidizing agents,we believe that a reaction between the peroxide and the reducingcompounds from the alkali treatment takes place causing oxidation ofcompounds that are responsible for objectionable flavor and color. Thevolatile compounds are removed by evaporation under vacuum while thecompounds responsible for color are oxidized to colorless compounds bythe peroxide.

Having fully described this new and unique invention, we claim:
 1. Aprocess for producing a proteinaceous mixture of modified plant proteinand unmodified protein, said mixture having thermoplastic and formingproperties similar to casein and caseinate salts, said processcomprising:a. making an aqueous slurry of a plant protein material, saidplant protein material containing steam volatile flavor components andat least about 30 percent by weight protein, said slurry having a solidscontent of from about 3 percent to about 18 percent by weight; b.adjusting the pH of the aqueous slurry to a pH in the range of fromabout 7.0 to about 10.5 by addition thereto of an alkali metalcarbonate; c. reacting the alkali metal carbonate with the plant proteinby heating the aqueous slurry to a temperature in the range of from 280°F. to 370° F. for from 2.5 to 5 minutes; d. cooling the reacted proteinslurry to a temperature below 130° F.; e. adding from 0.3 percent toabout 1.5 percent by weight peroxide to the slurry, said peroxide beinga member selected from the group consisting of hydrogen peroxide, sodiumperoxide, potassium peroxide, calcium peroxide, and magnesium peroxide;f. mixing the peroxide containing slurry; g. neutralizing the slurry toa pH within the range of from 6.6 to 7.0 by addition thereto of anedible acid; h. thereafter, removing the steam volatile flavorcomponents from the slurry by heating the slurry; i. drying theneutralized slurry to remove a substantial portion of the water therein;and j. admixing from 1 to 15 parts by weight of the substantially driedneutralized slurry with from 1 to 30 parts by weight proteinaceousmaterial not having been modified by reaction with an alkali metalcarbonate.
 2. A process as in claim 1 wherein the steam volatile flavorcomponents are removed from the slurry by heating the slurry under avacuum.
 3. A process as in claim 2 wherein the steam volatile flavorcomponents are removed from the slurry by heating the slurry to atemperature sufficient to accomplish boiling under a vacuum in the rangeof from 15 inches to 30 inches.
 4. A process as in claim 1 wherein theplant protein material is selected from the group consisting of oatprotein and oil seed vegetable protein.
 5. A process as in claim 1wherein the alkali metal carbonate in the slurry is reacted with theprotein by heating the aqueous slurry to a temperature of from 295° F.to 310° F. in a closed vessel for from 3.5 to 5.0 minutes.
 6. A processas in claim 1 wherein the plant protein material is a solvent extractedoil seed vegetable protein.
 7. A process as in claim 1 wherein theaqueous slurry has a protein content of up to about 12 percent byweight.
 8. A process as in claim 1 wherein the alkali metal carbonate isa member selected from the group consisting of sodium carbonate, sodiumbicarbonate, potassium carbonate, and potassium bicarbonate.
 9. Aprocess as in claim 1 wherein the plant protein is soy protein isolate.10. A process as in claim 1 wherein the plant protein material is an oatprotein.
 11. A process as in claim 1 wherein the slurry is neutralizedimmediately after the protein in the slurry is reacted with the alkalimetal carbonate.
 12. A process for producing a proteinaceous mixture ofmodified plant protein and unmodified protein, said mixture havingthermoplastic and forming properties similar to casein and caseinatesalts, said process comprising:a. making an aqueous slurry of a plantprotein material, said plant protein material containing steam volatileflavor components and at least about 30 percent by weight protein, saidslurry having a solids content of from about 3 percent to about 18percent by weight; b. adjusting the pH of the aqueous slurry to a pH inthe range of from about 7.0 to about 10.5 by addition thereto of analkali metal carbonate; c. reacting the alkali metal carbonate with theplant protein by heating the aqueous slurry to a temperature in therange of from 280° F. to 370° F. for from 2.5 to 5 minutes; d. addingfrom 0.3 percent to about 1.5 percent by weight peroxide to the slurry,said peroxide being a member selected from the group consisting ofhydrogen peroxide, sodium peroxide, potassium peroxide, calciumperoxide, and magnesium peroxide; e. mixing the peroxide containingslurry; f. neutralizing the slurry to a pH of from 6.6 to 7.0 byaddition thereto of an edible acid; g. thereafter, removing the steamvolatile flavor components from the slurry by heating the slurry under avacuum; h. drying the neutralized slurry to remove a substantial portionof the water therein; and i. admixing from 1 to 15 parts by weight ofthe substantially dried neutralized slurry with from 1 to 30 parts byweight proteinaceous material not having been modified by reaction withan alkali metal carbonate.
 13. A process for producing a proteinaceousmixture of modified plant protein and unmodified protein, said mixturehaving thermoplastic and forming properties similar to casein andcaseinate salts, said process comprising:a. making an aqueous slurry ofa plant protein material, said plant protein material containing steamvolatile flavor components and at least about 30 percent by weightprotein, said slurry having a solids content of from about 3 percent toabout 18 percent by weight; b. adjusting the pH of the aqueous slurry toa pH in the range of from about 7.0 to about 10.5 by addition thereto ofan alkali metal carbonate; c. reacting the alkali metal carbonate withthe plant protein by heating the aqueous slurry to a temperature in therange of from 280° F. to 370° F. for from 2.5 to 5 minutes; d. coolingthe reacted protein slurry to a temperature below 130° F.; e. addingfrom 0.3 percent to about 1.5 percent by weight peroxide to the slurry,said peroxide being a member selected from the group consisting ofhydrogen peroxide, sodium peroxide, potassium peroxide, calciumperoxide, and magnesium peroxide; f. mixing the peroxide containingslurry; g. neutralizing the slurry to a pH within the range of from 6.6to 7.0 by addition thereto of an edible acid; h. thereafter, removingthe steam volatile flavor components from the slurry by heating theslurry; and i. admixing from 1 to 15 parts by weight of thesubstantially dried neutralized slurry with from 1 to 30 parts by weightproteinaceous material not having been modified by reaction with analkali metal carbonate.